Apparatus for feeding gases for use in semiconductor manufacturing

ABSTRACT

An apparatus for feeding gases for use in semiconductor manufacturing reduced in size and manufacturing costs and facilitating maintenance and operation of the gas supply system. The apparatus comprises a plurality of gas supply sources, gas source valves provided on the gas lead-out pipes from the respective gas supply sources, flow rate controllers provided on main gas feed pipes into which the lead-out pipes converge, and gas supply valves provided on the outlet side of the flow rate controllers.

FIELD OF THE INVENTION

The present invention relates to improved apparatuses and methods forfeeding gases. More specifically, in one embodiment this inventionrelates to feeding or supplying a plurality of different types of gasesone after another through a single gas feed pipe by switching the gastype from one to another at specific time intervals. In anotherembodiment, this invention relates to feeding or supplying a single typeof gas through one or a plurality of pipes or any combination of pipesin any sequence of switching pipes. With the flow rates controlled bymeans of a single flow rate controller in semiconductor manufacturingfacilities, this offers such advantages as reduction in the size andmanufacturing costs of the gas feeder.

BACKGROUND OF THE INVENTION

In semiconductor manufacturing, many types of gases are used indifferent ways. For example, a number of different types of gases aredrawn, not all at once but one after another in a series fashion byswitching the gas type from one to another at specific time intervals.Also, one and the same type of gas is often used at different flow ratessimultaneously or in parallel. In those applications, the flow ratesmust be controlled with high accuracy.

In prior art gas feeding apparatuses for use in semiconductormanufacturing, flow rate controllers such as mass flow rate controllersare installed, one on each gas line, to control the flow rate with highaccuracy.

In etching, one of the important processes in semiconductormanufacturing, for example, a plurality of insulating films are etched.This process is made up of a number of etching steps. In each step, 3 or4 types of gases are used in combination. To supply those gases, priorart gas feeders require a total of more than 10 gas and flow ratecontrollers in the etching process alone. A vast number of suchcontrollers have to be installed to serve an entire semiconductormanufacturing plant.

In the Chemical Vapor Deposition (CVD) process, a type of gas issupplied to a treatment reactor at one or different flow rates through aplurality of outlets simultaneously to carry out a CVD treatment. Theprior art gas feeder has a flow rate controller installed at everyoutlet line to regulate the flow rates. Here, also, too many flow ratecontrollers are needed. To a single treatment reactor for the CVDprocess, in addition, a plurality of types of gases may also be suppliedin a series fashion. That likewise requires quite a number of flow ratecontrollers.

Heretofore, mass flow rate controllers had been the primary flow ratecontrollers used. In recent years, so-called pressure-type flow controlsystems have become more common.

The installation of a large number of flow rate controllers not onlyincreases the size of the gas feeder but also makes it difficult to keepdown the costs both of the feeder itself and of facility maintenance andservice costs. This also presents such problems as increased labor inmaintenance and the necessity of keeping many replacement and spareparts in stock, which inevitably raises the running costs of the gasfeeder.

The present invention addresses those problems encountered with theprior art apparatuses and methods for feeding gases in semiconductormanufacturing plants, that is, the necessity of installing too many flowrate controllers, one for each outlet line, which has prohibited sizereduction of the gas feeding equipment and reduction of the costs of theequipment itself.

SUMMARY OF THE INVENTION

It is accordingly a primary object of the present invention to providean apparatus and method for feeding gases for use in semiconductormanufacturing. This novel apparatus and method, by means of only a fewflow rate controller units, controls many different types of gases ordifferent flow rates of the same gas in semiconductor manufacturing withhigh accuracy. Moreover, the novel apparatus and method permits areduction in the size of the gas feeder itself and a substantialreduction in the manufacturing costs of the equipment.

The object of the invention is achieved by installing a single flow ratecontroller in a single process consisting of a number of steps or agroup of common steps in the respective processes, thereby controllingthe gas flow rates so as to supply one and the same type of gas or aplurality of different types of gases to each process or step one afteranother, by switching the gas flow path or gas type from one to anotherat specific time intervals, and also by making arrangements so that manydifferent types of gases or significantly different flow rates of oneand the same gas are dealt with or controlled with high accuracy andsupplied through one or a plurality of feed ports.

In each semiconductor manufacturing process or in steps in the process,many different types of gases are used. They are generally used,however, not all at a time but one after another or in a series fashion.That is, the flow of gases to a process is switched from one type of gasto another type of gas at specific time intervals. Even a single flowrate controller can control different flow rates of one type of gas orthe flow of a plurality of gases with high accuracy, if the flowcharacteristics can be automatically switched and compensated orswitched and adjusted to cope with the change in gas type or flow rate.

The apparatus for feeding gases for use in semiconductor manufacturingas defined in one embodiment is basically constituted of a plurality ofgas supply sources, gas source valves provided on the respectivelead-out pipes, a flow rate controller provided on the main gas feedpipe into which the lead-out pipes converge, and a gas feed valvemounted on the outlet side of the flow rate controller. Preferredly, aplurality of units of this apparatus for feeding gas are arranged inparallel and each gas feeder supplies different types of gases as neededto the semiconductor manufacturing facilities.

The apparatus for feeding gases for use in semiconductor manufacturingin another embodiment is basically constituted of a unit of gas supplysource, a flow rate controller installed on the main gas feed pipe fromthe gas supply source, and a plurality of gas feed valves provided onthe outlet side of the flow rate controller in the shape of a pluralityof parallel branches. Preferredly, a plurality of units of thisapparatus too for feeding gas are arranged in parallel and each gasfeeder supplies different types of gases as needed to the semiconductormanufacturing facilities.

In both of the above embodiments of the invention, the flow ratecontroller may be either a mass flow controller or a pressure-typecontroller.

When a pressure-type controller is used in this invention, thepressure-type flow control system may comprise a control valve CVprovided on the main gas feed pipe, a pressure detector 14 provided onthe downstream side from the control valve CV, a plurality of orifices 2a, 2 b, . . . provided in parallel on the downstream side from thepressure detector 14, a flow rate calculation circuit 20 for calculatingthe flow rate Qc=KP1 (where K is a constant) from the pressure P1detected at the pressure detector 14, a flow rate setting circuit 32 foroutputting a flow rate setting signal Qs, and a calculation controlcircuit 38 for outputting the difference between the calculation flowrate signal Qc and the flow rate setting signal Qs as control signal Qyto the drive 8 of the control valve CV. The control valve CV is operatedto bring the control signal Qy to zero, thereby controlling the flowrates on the downstream side from the orifices 2 a, 2 b . . . and at thesame time selecting the orifice with the bore matching with the gas flowrate out of the plurality of orifice 2 a, 2 b . . . and actuating thesame.

In the above-described apparatuses, the pressure-type flow controlsystem may be configured so that one or a plurality of orifices areprovided in the shape of branches and installed on the downstream sidefrom the gas feed valve. In this case, a plurality of units of theorifice may be provided in the shape of branches at the inlet of orinside of the treatment reactor on the downstream side from the gas feedvalve.

Still another embodiment of the present invention is a method forfeeding gases for use in semiconductor manufacturing, which methodcomprises providing a single flow rate controller for gas supply in eachsemiconductor manufacturing process or in a group of common steps in theprocesses and wherein, with the flow rates regulated by the flow ratecontroller, one type or plurality of types of gases are switched andsupplied one after another to each process or each common step group atspecific time intervals. In carrying out this method, a single type or aplurality of types of gases may be supplied to a single treatmentreactor from a plurality of feed ports. Further, in implementing thismethod, one may work out in advance the flow rate controlcharacteristics of the mass flow controller in the form of data for eachtype of gas to be supplied and each flow rate, store those data in astorage of a control computer, retrieve the flow rate characteristicsmatching for the type of gas or flow rate to be switched over to fromthe computer storage when the gas type or flow rate is switched, andregulate the flow rate of gas according to the flow ratecharacteristics.

In accordance with the method of the present invention in which the flowrate controller is of the pressure-type, one may work out in advance theflow factor FF in relation to a reference gas (e.g., nitrogen gas) foreach type of gas to be supplied and, when the gas type is switched,bring the flow rate specifying signal Qs after the switching to kQe,that is Qs=kQe in which Qe is the flow rate setting signal for thereference gas and k is the flow rate conversion rate.

When the flow rate controller herein is of the pressure-type, it may beprovided with a plurality of orifices with different bores in paralleland those orifices may be selectively activated according to the flowrate of the gas to be switched over to.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic flow diagram of the configuration of an apparatusfor feeding gases for use in semiconductor manufacturing of a firstembodiment of the present invention, with part of the apparatus omitted.

FIG. 2 is a schematic flow diagram of the configuration of an apparatusfor feeding gases for use in semiconductor manufacturing of a secondembodiment of the present invention, with part of the apparatus omitted.

FIG. 3 is a schematic flow diagram of the configuration of an apparatusfor feeding gases for use in semiconductor manufacturing of a thirdembodiment of the present invention, with part of the apparatus omitted.

FIG. 4 is a schematic flow diagram of the basic configuration of thepressure-type flow control system used in the present invention.

FIG. 5 is a schematic flow diagram of the basic configuration of anapparatus for feeding gases of a fourth embodiment of the presentinvention in which a pressure-type flow control system is used.

FIG. 6 is a schematic flow diagram of the basic configuration of apressure-type flow control system in another embodiment of the presentinvention.

FIG. 7 is a schematic flow diagram of the configuration of an apparatusfor feeding gases for use in semiconductor manufacturing of a fifthembodiment of the present invention.

FIG. 8 is a schematic flow diagram of the configuration of an apparatusfor feeding gases for use in semiconductor manufacturing of a sixthembodiment of the present invention.

FIG. 9 is a schematic flow diagram of the basic configuration of thepressure-type flow control system used in an another embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, various illustrative embodiments of the present invention will bedescribed with reference to the drawings.

EXAMPLE 1

FIG. 1 shows a first embodiment of the present invention. In FIG. 1, RRis a treatment reactor forming part of semiconductor manufacturingfacilities and A1, A2, A3 are individual apparatuses for feeding gasesto the treatment reactor RR. That is, the gas feeders A1, A2, and A3supply the gases needed for treatment steps B1, B2, and B3 to be carriedout in the treatment reactor RR. For example, when the treatment step B1is to be carried out in the treatment reactor RR, the gas feed valve V1will be opened while the feed valves V2 and V3 will be closed. Thengases G1, G2, G3, and G4 are switched and supplied one after another tothe treatment reactor RR at specific time intervals.

In FIG. 1, G1, G2, G3, and G4 are different supply gas sources, each fora different type gas: G1 for oxygen, G2 for hydrogen, G3 for nitrogen,and G4 for SiH₄, for example.

MFC is a mass flow controller forming a flow rate controller FRC. VG1,VG2, VG3, and VG4 are gas source valves. L1, L2, L3, and L4 are gaslead-out pipes. Lo is a main gas feed pipe. F1, F2, and F3 are gastake-off ports. And V1, V2, and V3 are gas feed valves.

The mass flow controller MFC making up the flow rate controller FRCitself is already known and no detail will be described. But it is notedthat the mass flow controller MFR used in the present invention has lotsof prepared flow rate control characteristic curves on every type of gasand every gas flow rate stored in the storage of a control computerattached thereto. When the type of gas or the flow rate is switched fromone to another, the flow rate control is automatically retrieved fromthe storage in the computer (not shown). On the basis of the retrievedflow rate control characteristics, the flow rate of the gas to beswitched over to is controlled with adjustment made to such functions aslinear riser in the mass flow controller MFC.

In the embodiment shown in FIG. 1, when the gas type or the flow rate ofgas is switched, the linear riser in the mass flow controller MFC is soadjusted as to conform the flow rate characteristics of the mass flowcontroller MFC to the flow rate characteristics prepared in advance onevery gas type. But another procedure is also possible. It is this: Theflow rate control characteristic curves in the mass flow controller MFCare fixed on only the gas types and the flow rates conforming to thestandard. For the gas types or flow rates outside the standard, theirconversion factors against the standard gases are worked out and storedin advance so that when the gas type or the flow rate is changed, anapproximate control parameter corresponding to the standard gas and thestandard flow rate is calculated on the basis of the measurements atthat time and the conversion factors. According to that approximatecontrol parameter, the flow rate of the non-standard gas is controlled.

In FIG. 1, three gas feeders A1, A2, and A3 are combined in parallel toconstitute a gas supply battery. In practice, a gas supply battery isgenerally formed of three to ten gas feeders.

EXAMPLE 2

FIG. 2 shows a second embodiment of the present invention. It is soconfigured that one gas supply source G1 supplies one and the same typeof gas at specific rates simultaneously to a plurality of gas feed portsprovided on the treatment reactor RR through a flow rate controller FRC,a main gas feed pipe Lo and a plurality of gas feed valves V1 to V4 onbranch pipes. The feed path may be switched from a specific port orports to another at specific time intervals, too.

In FIG. 2, three gas feeders A1, A2, and A3 are installed in parallel.In practice, five to ten feeders are arranged in parallel to form abattery of gas feeders as in FIG. 1.

EXAMPLE 3

FIG. 3 shows a third embodiment of the present invention. In thisembodiment, a pressure-type flow control system FCS is used as flow ratecontroller FRC instead of the mass flow controller MFC used in FIG. 1.

The gas feeder A in FIG. 3 is exactly the same as that in FIG. 1 exceptthat the flow rate controller FRC installed is a pressure-type flowcontrol system FCS, and not the mass flow controller MFC, and so therewill be no detailed description of the gas feeder.

FIG. 4 is a schematic flow diagram of the configuration of thepressure-type flow control system FCS which is used in the gas feedersshown in FIG. 3.

In FIG. 4, if the ratio between the gas pressures before and after anorifice 2, that is, the ratio of the downstream gas pressure P2 ito theupstream gas pressure P1, falls below the critical gas pressure ratio(in the case of air, nitrogen, etc., about 0.5), the flow velocity ofthe gas passing the orifice will reach sonic velocity. As a result, thefluctuation in pressure on the downstream side of the orifice 2 will bedifficult to convey to the upstream side, and that will bring about astable mass flow rate on the downstream side matching with the state onthe upstream side of the orifice 2.

That is, if, with a fixed bore of the orifice 2, the upstream pressureP1 is set at about twice or more than twice the downstream pressure P2,the downstream flow rate Qc of the gas passing the orifice 2 will dependon only the upstream pressure P1 and the linear relationship Qc=KP1 willhold good to the highest degree. If the bore of the orifice is fixed,the constant K will be fixed.

The flow path 4 on the upstream side of the orifice 2 is connected to acontrol valve CV which is operated by a drive 8, while the flow path 6on the downstream side is connected to the treatment reactor (not shown)via an orifice-responding valve 10 and a gas take-off joint 12.

The pressure P1 on the upstream side of the orifice 2 is detected by thepressure detector 14, and amplified by an amplification circuit 16 anddisplayed on a pressure display 22. The output is passed on to ananalog-digital (A-D) converter to be digitalized, from which the flowrate Q on the downstream side of orifice, that is, Q−KP1 (K: constant)is calculated by a calculation circuit 20.

On the other hand, the temperature T1 on the upstream side is detectedby a temperature detector 24 and output through an amplification circuit26 and an A-D converter 28 to a temperature compensation circuit 30,where the flow rate Q is temperature-compensated. The calculated flowrate Qc is output to a comparison circuit 36. Here, the calculationcircuit 20, the temperature compensation circuit 30 and the comparisoncircuit 36 make up a calculation control circuit 38.

A flow rate setting circuit 32 outputs a flow rate Qs through an A-Dconverter 34 to the comparison circuit 36. The comparison circuit 36calculates a difference signal Qy between the calculated flow rate Qcand the set flow rate Qs, that is, Qy=Qc−Qs, and outputs the result tothe drive 8 through an amplification circuit 40. The drive 8 so operatesthe control valve CV as to bring the difference signal Qy to zero sothat the flow rate on the downstream side of the orifice is equal to theset flow rate.

This pressure-type flow control system FCS is so designed that the flowrate on the secondary side of the orifice 2 is controlled throughadjustment of the pressure P1 on the upstream side thereof. That permitscontrol of the flow rate on the downstream side of the orifice 2 withoutbeing influenced by the gas pressure on the upstream side of the controlvalve CV and gives flow rate characteristics with a relatively highlinearity.

For different types of gases or flow rates, the so-called flow factorsagainst the standard gases and standard flow rates are prepared andstored. With that, the pressure-type flow control system FCS can alsoexercise flow rate control on different types of gases or flow rateswith relative ease and high accuracy.

EXAMPLE 4

FIG. 5 shows a fourth embodiment of the present invention. In thisembodiment, a pressure-type flow control system FCS is used as flow ratecontroller FRC and it is so configured that the orifice 2, an componentof the pressure-type flow control system, is provided at the inlet of orinside of the treatment reactor RR on the downstream side of the gasfeed valve V1.

One orifice 2 or more may be provided at the inlet of or inside of thetreatment reactor RR, but two or more orifices would be convenient, forthat would permit adjustment to any flow rate of the flow of gas to bedischarged into the respective regions within the treatment reactor RR.

Two or more orifice, each with a different bore, would make it possibleto control different flow rates of gas with one pressure-type flowcontrol system FCS.

FIG. 6 is a schematic flow diagram of the configuration of thepressure-type flow control system FCS used in the fourth embodiment ofthe present invention shown in FIG. 5. It is different from the one inFIG. 4 in that the orifice 2 in FIG. 6 is provided at the inlet of orinside of the treatment reactor RR on the downstream side of theorifice-responding valve 10. In other points, the controller FCS in FIG.6 is identical with that in FIG. 4. In case the cross-sectional area ofthe treatment reactor is so large as to require facilitation of thedistribution of the flow rate of the discharge gas, the pressure-typeflow control system FCS configured as FIGS. 4 and 6 is used asmentioned.

EXAMPLE 5

FIG. 7 shows a fifth embodiment of the present invention. In thisembodiment, a pressure-type flow control system FCS is used as flow ratecontroller FRC and it is so configured that the gas type is switchedamong G1, G2, G3, and G4 to supply each gas at a different flow rate tothe treatment reactor RR.

In FIG. 7, the same component parts as those in FIGS. 3 and 4 areindicated by the common reference numbers.

That is, 2 a, 2 b, 2 c, and 2 d in FIG. 7 are orifices. Those fourorifices are different in bore and ranked in that order with 2 a beingthe largest and 2 d the smallest. 10 a, 10 b, 10 c, and 10 d areorifice-responding valves. F1 a, F1 b, F1 c, and F1 d are gas take-offports. V1 a to V1 d are gas feed valves. While it is so configured inFIG. 7 that orifices 2 a, 2 b, 2 c, and 2 d are different from eachother in bore, two or more of them, needless to say, may be identical inbore.

In case a gas, nitrogen for example, is to be supplied from a gas sourcearray consisting of G1, G2, G3, and G4 to the treatment reactor RR at ahigh flow rate, the gas flow rate is controlled this way: theorifice-responding valve 10 a and the gas feed valve V1 a are openedwhile the orifice-responding values 10 b, 10 c, and 10 d and the gasfeed valves V1 b, V1 c, and V1 d are closed to actuate the orifice 2 aso as to bring the flow rate of the gas supply to the set flow rate Qsa(maximum flow rate).

Similarly, when a gas, say, O2 is supplied from the gas source arrayconsisting of G1, G2, G3, and G4 to the treatment reactor RR for theminimum flow rate of a gas at the minimum flow rate, theorifice-responding valve 10 d and the gas feed valve V1 d are openedwhile the orifice-responding values 10 a, 10 b, and 10 c and the gasfeed valves V1 a, V1 b, and V1 c are closed to actuate the orifice 2 dso as to bring the flow rate of the gas supply from the O2 source G4 tothe set flow rate Qsd (minimum flow rate).

The set flow rates Qsa, Qsb, Qsc, and Qsd for the gases from G1 to G4are freely set according to the needs at the treatment reactor RR. Thefull scale on the pressure-type flow control system FCS is switched asby properly adjusting the amplification degree of the output amplifier16 for the pressure detector 14, for example, according to the sizes ofthe set flow rate Qs to Qsd.

EXAMPLE 6

FIG. 8 shows a sixth embodiment of the present invention. Thisembodiment is provided with four groups of gas sources, each groupconsisting of four different type gas sources, for example, G1 forhydrogen, G2 for oxygen, G3 for nitrogen and G4 for SiH₄ and is soconfigured that those gases are supplied to the treatment reactor RR atdifferent flow rates.

That is, in FIG. 8, four units of the gas feeder shown in FIG. 6 whichis provided with four different gas sources G1, G2, G3, and G4 arearranged in parallel and are each equipped with three orifices 2 a, 2 b,and 2 c, each with a different bore, for setting the flow rates.

As in FIG. 1, any two of the orifices 2 a, 2 b and 2 c can be identicalin bore.

In the embodiment shown in FIG. 8, furthermore, it is possible to supplyto the treatment reactor RR different gases from the different gassources G1, G2, G3, and G4 simultaneously by actuating all thepressure-type flow control systems FCS1, FCS2, FCS3, and FCS4 or in aseries fashion by repeating selection and actuation of one or more fromthose flow control systems. Needless to say, the respectivepressure-type flow control systems FCS1, FCS2, FCS3, and FCS4 select theorifice 2 a, 2 b, or 2 c having the bore which matches for the gas flowrate required.

The full scale on the pressure-type flow control systems FCS1, FCS2,FCS3 and FCS4 can be freely switched according to the selected orificebore, that is, the gas flow rate just the same way as in FIG. 3 and FIG.7.

EXAMPLE 7

FIG. 9 shows a further embodiment of the pressure-type flow controlsystem used in the present invention. This embodiment is the same as thepressure-type flow control system shown in FIG. 4 except that a flowrate conversion circuit 39 is provided between the flow rate-settingcircuit 32 and the comparison circuit 36.

The flow rate conversion circuit 39 is to make the full scale flow ratevariable.

In case the conversion rate k of the flow rate conversion circuit 39 is1, that is, the full scale flow rate is not switched yet, thecalculation circuit 20 calculates the flow rate Q from the pressuresignal P1 by the equation Q=KP1. At the same time, the flow rate Q istemperature-compensated by a compensation signal from the temperaturecompensation circuit 30, and the calculated flow rate Qc is output tothe comparison circuit 36.

In case the conversion rate K in the flow rate conversion circuit 39 isset at the constant K, the signal Qe is converted into the flow ratespecifying signal Qs (Qs=kQe) through the flow rate conversion circuit39, and this flow rate specifying signal Qs is inputted in thecalculation control circuit 38.

The constant K represents the flow rate conversion rate and is providedto make the full scale flow rate variable. Therefore, the flow rateconversion circuit 39 can vary the flow rate conversion rate kcontinuously or in stages. For the variation in stages, a dip switch,for example, can be used.

The flow rate conversion rate k set by the flow rate conversion circuit39 for nitrogen gas, helium gas, CF₄ gas, etc. is varied in stages andis related to the flow factor FF of each gas which will be describedlater.

That is, the flow factor FF indicates how many times the flow rate ofnitrogen gas the flow rate of such working gases as helium and CF₄represents with the same bore of the orifice 2 and the same pressure P1on the upstream side. It can be defined as FF=flow rate of workinggas/that of nitrogen.

To be concrete, here are some examples of the factor FF: N₂=1, Ar=0.887,He=2.804, CF₄=0.556, C₄F₈=0.344.

If the orifice 2 in the pressure-type flow control system of the presentinvention is 90 microns, for example, and the control pressure, that is,P1 is 1.8 (kgf/cm2abs), the flow rate of nitrogen gas is 125.9 SCCMaccording to the results of experiments. This means that with thenitrogen gas, the full scale flow rate is 125.9 SCCM. This is set as100% of the flow rate setting signal Qe with the voltage at 5 V. Sincethe flow rate conversion rate k is set at 1 (k=1) for nitrogen gas, theflow rate specifying signal Qs is 100% with the full scale at 125.9SCCM, because Qs=kQe.

Now, there will be considered the switching of supply gases fromnitrogen gas to helium gas with that orifice 2 and under the pressureP1. Suppose that the flow rate of helium gas to supply is 300 SCCM, forexample, the flow factor FF of helium is 300 SCCM/2.804=107.0 SCCM.

Meantime, since 125.9 of SCCM of nitrogen gas is the full scale range inthe present embodiment as mentioned earlier, the flow rate conversionrate K for helium is set as follows: 107.0 SCCM/125.9 SCCM=0.850.

As a result, the flow rate specifying signal Qs is Qs=0.850×Qe=0.850×300SCCM, and the voltage is 5 B×0.850.

In the embodiment shown in FIG. 9, the flow factor FF of each supply gasagainst the reference gas nitrogen is worked out and stored, on thebasis of which the flow rate conversion rate k is calculated for thetype and the flow rate of the supply gas to be switched over to asmentioned. Setting the flow rate conversion rate in the flow rateconversion circuit at the calculated value K makes it possible toregulate the flow rate of the gas to be switched over to at the set flowrate Qe to continue the flow of gas.

In the embodiments shown in FIGS. 1 to 9, the mass flow controller MFCor the pressure-type flow control system FCS is used as flow ratecontroller FRC. The flow rate controller FRC is not limited to those twotypes but may be of any configuration such as, for example, thegeneral-use flow rate controller made up of a combination of valves,orifices and detection sensors to detect the difference between thepressures before and after the orifice.

Also, the embodiments shown in FIGS. 4 to 9 are provided withorifice-responding valves 10 a to 10 d and gas feed valves V1 a to V1 c.But the orifice-responding valves 10 a to 10 d may be omitted, and theorifices 2 a to 2 d, a pressure detector P or the like may be properlyincorporated in the valve bodies of the gas feed valves V1 a to V1 d.

EFFECT OF THE INVENTION

The apparatuses or a method for feeding gases for use at semiconductormanufacturing facilities as disclosed and claimed herein are configuredso that a plurality of types of gases are grouped and the gases withinthe group are supplied through a flow rate controller one after anotherto a semiconductor treatment reactor, or so that one type of gas iscontrolled by a flow rate controller and supplied through different flowpaths either simultaneously or in a series fashion. This is to becompared with prior art gas feeders provided with a flow rate controlleron every gas line to the semiconductor manufacturing facility. Thus, thepresent invention permits size reduction and cost reduction of the gasfeeder and besides substantially cuts down the maintenance costs of theequipment.

The present invention can cope with a change of gas types and majorchange in gas flow rate with one and the same flow rate controller withrelative ease and thus allow continuation of flow rate control with highaccuracy. Likewise, the present invention can respond to not only achange of gas types but also to a major change in gas flow rate veryeasily, and can maintain high accuracy flow rate control even when thereis a change of gas types and gas flow rates.

This invention additionally permits free adjustment of the distributionof the gas discharge flow rate within the treatment reactor, and thusenables processing steps to proceed in a semiconductor manufacturingfacility with high accuracy.

What is claimed is:
 1. An apparatus for feeding gases for use insemiconductor manufacturing facilities comprising a plurality of gassupply sources, gas source valves provided on gas lead-out pipes fromsaid respective gas supply sources, a flow rate controller provided on amain gas feed pipe into which the lead-out pipes converge, and a gasfeed valve provided on an outlet side of the flow rate controller;wherein the flow rate controller is a pressure-type flow controllercomprising: a control valve provided on the main gas feed pipe; apressure detector provided on a downstream side of the control valve; aplurality of orifices provided on the downstream side of the pressuredetector in parallel; a flow rate calculation circuit for calculatingthe flow rate Qc given by the equation Qc=KP1 from the pressure P1 foundby said pressure detector and the constant K; a flow rate settingcircuit for outputting a flow setting signal corresponding to a set gasflow rate; and a calculation control circuit for outputting to a driveof the control valve a control signal comprising the difference betweensaid calculation flow rate and the flow rate setting signal; and whereinthe control valve is operable to bring the control signal to zero,thereby to control the flow rates on the downstream sides of theplurality of orifices and at the same time to select an orifice with abore that matches the set gas flow rate out of said plurality oforifices and to actuate the orifice so selected.
 2. An apparatus forfeeding gases for use in semiconductor manufacturing facilities asdefined in claim 1, further comprising a treatment reactor having aninlet, wherein one orifice or a plurality of orifices are provided inthe shape of branches at the inlet of the treatment reactor.
 3. Anapparatus for feeding gases for use in semiconductor manufacturingfacilities as defined in claim 1, further comprising a treatment reactorhaving an inlet, wherein one orifice or a plurality of orifices areprovided in the shape of branches inside of the treatment reactor.
 4. Anapparatus for feeding gases for use in semiconductor manufacturingfacilities comprising a plurality of gas feeders arranged in parallel,each gas feeder to supply different gases needed, each said gas feederhaving a plurality of gas supply sources, gas source valves provided ongas lead-out pipes from said respective gas supply sources, a flow ratecontroller provided on a main gas feed pipe into which said lead-outpipes are converged and a gas feed valve provided on an outlet side ofthe flow rate controller; wherein the flow rate controller is apressure-type flow controller comprising: a control valve provided onthe main gas feed pipe; a pressure detector provided on a downstreamside of the control valve; a plurality of orifices provided on thedownstream side of the pressure detector in parallel; a flow ratecalculation circuit for calculating the flow rate Qc given by theequation Qc=KP1 from the pressure P1 found by said pressure detector andthe constant K; a flow rate setting circuit for outputting a flowsetting signal corresponding to a set gas flow rate; and a calculationcontrol circuit for outputting to a drive of the control valve a controlsignal comprising the difference between said calculation flow rate andthe flow rate setting signal; and wherein the control valve is operableto bring the control signal to zero, thereby to control the flow rateson the downstream sides of the plurality of orifices and at the sametime to select an orifice with a bore that matches the set gas flow rateout of said plurality of orifices and to actuate the orifice soselected.
 5. An apparatus for feeding gases for use in semiconductormanufacturing facilities as defined in claim 4, further comprising atreatment reactor having an inlet, wherein one orifice or a plurality oforifices are provided in the shape of branches at the inlet of thetreatment reactor.
 6. An apparatus for feeding gases for use insemiconductor manufacturing facilities as defined in claim 4, furthercomprising a treatment reactor having an inlet, wherein one orifice or aplurality of orifices are provided in the shape of branches inside ofthe treatment reactor.
 7. An apparatus for feeding gases for use insemiconductor manufacturing facilities comprising a gas supply source, aflow rate controller provided on a supply pipe from said gas supplysource, and a plurality of gas feed valves provided on an outlet side ofsaid flow rate controller in the shape of parallel branches; wherein theflow rate controller is a pressure-type flow controller comprising: acontrol valve provided on the main gas feed pipe; a pressure detectorprovided on a downstream side of the control valve; a plurality oforifices provided on the downstream side of the pressure detector inparallel; a flow rate calculation circuit for calculating the flow rateQc given by the equation Qc=KP1 from the pressure P1 found by saidpressure detector and the constant K; a flow rate setting circuit foroutputting a flow setting signal corresponding to a set gas flow rate;and a calculation control circuit for outputting to a drive of thecontrol valve a control signal comprising the difference between saidcalculation flow rate and the flow rate setting signal; and wherein thecontrol valve is operable to bring the control signal to zero, therebyto control the flow rates on the downstream sides of the plurality oforifices and at the same time to select an orifice with a bore thatmatches the set gas flow rate out of said plurality of orifices and toactuate the orifice so selected.
 8. An apparatus for feeding gases foruse in semiconductor manufacturing facilities as defined in claim 7,further comprising a treatment reactor having an inlet, wherein oneorifice or a plurality of orifices are provided in the shape of branchesat the inlet of the treatment reactor.
 9. An apparatus for feeding gasesfor use in semiconductor manufacturing facilities as defined in claim 7,further comprising a treatment reactor having an inlet, wherein oneorifice or a plurality of orifices are provided in the shape of branchesinside of the treatment reactor.
 10. An apparatus for feeding gases foruse in semiconductor manufacturing facilities comprising a plurality ofgas feeders arranged in parallel, each gas feeder to supply a differentgas needed, each said gas feeder comprising a gas supply source, a flowrate controller provided on a supply pipe from said gas supply source,and a plurality of gas feed valves provided on an outlet side of saidflow rate controller in the shape of parallel branches; wherein the flowrate controller is a pressure-type flow controller comprising: a controlvalve provided on the main gas feed pipe; a pressure detector providedon a downstream side of the control valve; a plurality of orificesprovided on the downstream side of the pressure detector in parallel; aflow rate calculation circuit for calculating the flow rate Qc given bythe equation Qc=KP1 from the pressure P1 found by said pressure detectorand the constant K; a flow rate setting circuit for outputting a flowsetting signal corresponding to a set gas flow rate; and a calculationcontrol circuit for outputting to a drive of the control valve a controlsignal comprising the difference between said calculation flow rate andthe flow rate setting signal; and wherein the control valve is operableto bring the control signal to zero, thereby to control the flow rateson the downstream sides of the plurality of orifices and at the sametime to select an orifice with a bore that matches the set gas flow rateout of said plurality of orifices and to actuate the orifice soselected.
 11. An apparatus for feeding gases for use in semiconductormanufacturing facilities as defined in claim 10, further comprising atreatment reactor having an inlet, wherein one orifice or a plurality oforifices are provided in the shape of branches at the inlet of thetreatment reactor.
 12. An apparatus for feeding gases for use insemiconductor manufacturing facilities as defined in claim 10, furthercomprising a treatment reactor having an inlet, wherein one orifice or aplurality of orifices are provided in the shape of branches inside ofthe treatment reactor.